The Dow Jones industrial average is essentially flat this year, having fallen 0.3 percent.

Merck leads with a 12.6 percent rise. It has benefited from several developments, including collaborations with three other drugmakers to test its experimental cancer drug, MK-3475, in combination with theirs. It's in a new class of drugs meant to restore the immune system's ability to identify and target cancer cells.

Boeing finished the first quarter in last place, but shares jumped 2.2 percent Tuesday on news of a $6.5 billion order from Air Canada.